Elastic substantially linear olefin polymers

ABSTRACT

Substantially linear olefin polymers having a melt flow ratio, I 10 /I 2 , ≧5.63, a molecular weight distribution, M w /M n , defined by the equation: M w /M n ≦(I 10 /I 2 )−4.63, and a critical shear stress at onset of gross melt fracture of greater than about 4×10 6  dyne/cm 2  and their method of manufacture are disclosed. The substantially linear olefin polymers preferably have at least about 0.01 long chain branches/1000 carbons and a molecular weight distribution from about 1.5 to about 2.5. The new polymers have improved processability over conventional olefin polymers and are useful in producing fabricated articles such as fibers, films, and molded parts.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 08/925,827filed Sep. 5, 1997, now abandoned which itself was a continuation of acontinuation of application Ser. No. 08/730,766 filed Oct. 16, 1996, nowU.S. Pat. No. 5,665,800, which itself is a continuation of applicationSer. No. 08/606,633 filed Feb. 26, 1996, now abandoned, which itself isa continuation of application Ser. No. 08/433,784 filed May 3, 1995, nowabandoned, which itself is a divisional of application Ser. No.08/370,051 filed Jan. 9, 1995, now U.S. Pat. No. 5,525,695, which itselfis a divisional of application Ser. No. 08/044,426 filed Apr. 7, 1993,now U.S. Pat. No. 5,380,810, which itself is a divisional of applicationSer. No. 07/776,130 filed Oct. 15, 1991, now U.S. Pat. No. 5,272,236,the disclosures of each of which is incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to elastic substantially linear olefin polymershaving improved processability, e.g., low susceptibility to meltfracture, even under high shear stress extrusion conditions. Methods ofmanufacturing these polymers are also disclosed.

BACKGROUND OF THE INVENTION

Molecular weight distribution (MWD), or polydispersity, is a well knownvariable in polymers. The molecular weight distribution, sometimesdescribed as the ratio of weight average molecular weight (M_(w)) tonumber average molecular weight (M_(n)) (i.e., M_(w)/M_(n)) can bemeasured directly, e.g., by gel permeation chromatography techniques, ormore routinely, by measuring I₁₀/I₂ ratio, as described in ASTM D-1238.For linear polyolefins, especially linear polyethylene it is well knownthat as M_(w)/M_(n) increases, I₁₀/I₂ also increases.

John Dealy in “Melt Rheology and Its Role in Plastics Processing” (VanNostrand Reinhold, 1990) page 597 discloses that ASTM D-1238 is employedwith different loads in order to obtain an estimate of the shear ratedependence of melt viscosity, which is sensitive to weight averagemolecular weight (M_(w)) and number average molecular weight (M_(n)).

Bersted in Journal of Applied Polymer Science Vol. 19, page 2167-2177(1975) theorized the relationship between molecular weight distributionand steady shear melt viscosity for linear polymer systems. He alsoshowed that the broader MWD material exhibits a higher shear rate orshear stress dependency.

Ramamurthy in Journal of Rheology, 30(2), 337-357 (1986), and Moynihan,Baird and Ramanathan in Journal of Non-Newtonian Fluid Mechanics, 36,255-263 (1990), both disclose that the onset of sharkskin (i.e., meltfracture) for linear low density polyethylene (LLDPE) occurs at anapparent shear stress of 1-1.4×10⁶ dyne/cm², which was observed to becoincident with the change in slope of the flow curve. Ramamurthy alsodiscloses that the onset of surface melt fracture or of gross meltfracture for high pressure low density polyethylene (HP-LDPE) occurs atan apparent shear stress of about 0.13 MPa (1.3×10⁶ dynes/cm²).

Kalika and Denn in Journal of Rheology, 31, 815-834 (1987) confirmed thesurface defects or sharkskin phenomena for LLDPE, but the results oftheir work determined a critical shear stress of 2.3×10⁶ dyne/cm²,significantly higher than that found by Ramamurthy and Moynihan et al.

International Patent Application (Publication No. WO 90/03414) publishedApr. 5, 1990, discloses linear ethylene interpolymer blends with narrowmolecular weight distribution and narrow short chain branchingdistributions (SCBDs). The melt processibility of the interpolymerblends is controlled by blending different molecular weightinterpolymers having different narrow molecular weight distributions anddifferent SCBDs.

Exxon Chemical Company, in the Preprints of Polyolefins VIIInternational Conference, page 45-66, Feb. 24-27, 1991, disclose thatthe narrow molecular weight distribution (NMWD) resins produced by theirEXXPOL™ technology have higher melt viscosity and lower melt strengththan conventional Ziegler resins at the same melt index. In a recentpublication, Exxon Chemical Company has also taught that NMWD polymersmade using a single site catalyst create the potential for melt fracture(“New Specialty Linear Polymers (SLP) For Power Cables,” a by MonicaHendewerk and Lawrence Spenadel, presented at IEEE meeting in Dallas,Tex., September, 1991).

Previously known narrow molecular weight distribution linear polymersdisadvantageously possessed low shear sensitivity or low I₁₀/I₂ value,which limits the extrudability of such polymers. Additionally, suchpolymers possessed low melt elasticity, causing problems in meltfabrication such as film forming processes or blow molding processes(e.g., sustaining a bubble in the blown film process, or sag in the blowmolding process etc.). Finally, such resins also experienced meltfracture surface properties at relatively low extrusion rates therebyprocessing unacceptably.

SUMMARY OF THE INVENTION

We have now discovered a new family of substantially linear olefinpolymers which have many improved properties and a method of theirmanufacture. The substantially linear olefin polymers have (1) high meltelasticity and, (2) relatively narrow molecular weight distributionswith exceptionally good processibility while maintaining good mechanicalproperties and (3) they do not melt fracture over a broad range of shearstress conditions. These properties are obtained without benefit ofspecific processing additives. The new polymers can be successfullyprepared in a continuous polymerization process using constrainedgeometry catalyst technology, especially when polymerized utilizingsolution process technology.

The improved properties of the polymers include improved melt elasticityand processability in thermal forming processes such as extrusion,blowing film, injection molding and blowmolding.

Substantially linear polymers made according to the present inventionhave the following novel properties:

a) a melt flow ratio, I₁₀/I₂, ≧5.63,

b) a molecular weight distribution, M_(w)/M_(n), defined by theequation:

M _(w) /M _(n)≦(I ₁₀ /I ₂)−4.63, and

c) a critical shear stress at onset of gross melt fracture of greaterthan about 4×10⁶ dyne/cm².

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a polymerization processsuitable for making the polymers of the present invention.

FIG. 2 plots data describing the relationship between I₁₀/I₂ andM_(w)/M_(n) for polymer Examples 5 and 6 of the invention, and fromcomparative examples 7-9.

FIG. 3 plots the shear stress versus shear rate for Example 5 andcomparative example 7, described herein.

FIG. 4 plots the shear stress versus shear rate for Example 6 andcomparative example 9, described herein.

FIG. 5 plots the heat seal strength versus heat seal temperature of filmmade from Examples 10 and 12, and comparative examples 11 and 13,described herein.

DETAILED DESCRIPTION OF THE INVENTION

Other properties of the substantially linear polymers include:

a) a density from about 0.85 grams/cubic centimeter (g/cc) to about 0.97g/cc (tested in accordance with ASTM D-792), and

b) a melt index, MI, from about 0.01 grams/10 minutes to about 1000gram/10 minutes.

Preferably the melt flow ratio, I₁₀/I₂, is from about 7 to about 20.

The molecular weight distribution (i.e., M_(w)/M_(n)) is preferably lessthan about 5, especially less than about 3.5, and most preferably fromabout 1.5 to about 2.5.

Throughout this disclosure, “melt index” or “I₂” is measured inaccordance with ASTM D-1238 (190/2.16); “I₁₀” is measured in accordancewith ASTM D-1238 (190/10).

The melt tension of these new polymers is also surprisingly good, e.g.,as high as about 2 grams or more, especially for polymers which have avery narrow molecular weight distribution (i.e., M_(w)/M_(n) from about1.5 to about 2.5).

The substantially linear polymers of the present invention can behomopolymers of C₂-C₂₀ olefins, such as ethylene, propylene,4-methyl-1-pentene, etc., or they can be interpolymers of ethylene withat least one C₃-C₂₀ α-olefin and/or C₂-C₂₀ acetylenically unsaturatedmonomer and/or C₄-C₁₈ diolefins. The substantially linear polymers ofthe present invention can also be interpolymers of ethylene with atleast one of the above C₃-C₂₀ α-olefins, diolefins and/or acetylenicallyunsaturated monomers in combination with other unsaturated monomers.

Monomers usefully polymerized according to the present inventioninclude, for example, ethylenically unsaturated monomers, acetyleniccompounds, conjugated or nonconjugated dienes, polyenes, carbonmonoxide, etc. Preferred monomers include the C₂₋₁₀ α-olefins especiallyethylene, propylene, isobutylene, 1-butene, 1-hexene,4-methyl-1-pentene, and 1-octene. Other preferred monomers includestyrene, halo- or alkyl substituted styrenes, tetrafluoroethylene,vinylbenzocyclobutane 1,4-hexadiene, and naphthenics (e.g.,cyclo-pentene, cyclo-hexene and cyclo-octene).

The term “substantially linear” polymers means that the polymer backboneis either unsubstituted or substituted with up to 3 long chainbranches/1000 carbons. Preferred polymers are substituted with about0.01 long chain branches/1000 carbons to about 3 long chainbranches/1000 carbons, more preferably from about 0.01 long chainbranches/1000 carbons to about 1 long chain branches/1000 carbons andespecially from about 0.3 long chain branches/1000 carbons to about 1long chain branches/1000 carbons.

Long chain branching is defined herein as a chain length of at leastabout 6 carbons, above which the length cannot be distinguished using¹³C nuclear magnetic resonance spectroscopy. The long chain branch canbe as long as about the same length as the length of the polymerback-bone.

Long chain branching is determined by using ¹³C nuclear magneticresonance (NMR) spectroscopy and is quantified using the method ofRandall (Rev. Macromol. Chem. Phys., C29 (2&3), p. 285-297), thedisclosure of which is incorporated herein by refrence.

“Melt tension” is measured by a specially designed pulley transducer inconjunction with the melt indexer. Melt tension is the load that theextrudate or filament exerts while passing over the pulley at thestandard speed of 30 rpm. The melt tension measurement is similar to the“Melt Tension Tester” made by Toyoseiki and is described by John Dealyin “Rheometers for Molten Plastics”, published by Van Nostrand ReinholdCo. (1982) on page 250-251.

The “rheological processing index” (PI) is the apparent viscosity (inkpoise) of a polymer measured by a gas extrusion rheometer (GER). Thegas extrusion rheometer is described by M. Shida, R. N. Shroff and L. V.Cancio in Polymer Engineering Science, Vol. 17, no. 11, p. 770 (1977),and in “Rheometers for Molten Plastics” by John Dealy, published by VanNostrand Reinhold Co. (1982) on page 77, both publications of which areincorporated by reference herein in their entirety. All GER experimentsare performed at a temperature of 190° C., at nitrogen pressures between5250 to 500 psig using a 0.0296 inch diameter, 20:1 L/D die. An apparentshear stress vs. apparent shear rate plot is used to identify the meltfracture phenomena. According to Ramamurthy in Journal of Rheology,30(2), 337-357, 1986, above a certain critical flow rate, the observedextrudate irregularities may be broadly classified into two main types:surface melt fracture and gross melt fracture.

Surface melt fracture occurs under apparently steady flow conditions andranges in detail from loss of specular gloss to the more severe form of“sharkskin”. Gross melt fracture occurs at unsteady flow conditions andranges in detail from regular (alternating rough and smooth, helical,etc.) to random distortions. For commercial acceptability, (e.g., inblown film products), surface defects should be minimal, if not absent.The critical shear rate at onset of surface melt fracture (OSMF) andonset of gross melt fracture (OGMF) will be used herein based on thechanges of surface roughness and configurations of the extrudatesextruded by a GER. Preferably, the critical shear stress at the OGMF andthe critical shear stress at the OSMF for the substantially linearethylene polymers described herein is greater than about 4×10⁶ dyne/cm²and greater than about 2.8×10⁶ dyne/cm², respectively.

For the polymers described herein, the PI is the apparent viscosity (inKpoise) of a material measured by GER at a temperature of 190° C., atnitrogen pressure of 2500 psig using a 0.0296 inch diameter, 20:1 L/Ddie, or corresponding apparent shear stress of 2.15×10⁶ dyne/cm². Thenovel polymers described herein preferably have a PI in the range ofabout 0.01 kpoise to about 50 kpoise, preferably about 15 kpoise orless.

The SCBDI (Short Chain Branch Distribution index) or CDBI (CompositionDistribution Branch Index) is defined as the weight percent of thepolymer molecules having a comonomer content within 50 percent of themedian total molar comonomer content. The CDBI of an polymer is readilycalculated from data obtained from techniques known in the art, such as,for example, temperature rising elution fractionation (abbreviatedherein as “TREF”) as described, for example, in Wild et al, Journal ofPolymer Science, Poly. Phys. Ed., Vol. 20, p. 441 (1982), or in U.S.Pat. No. 4,798,081, both disclosures of which are incorporated herein byreference. The SCBDI or CDBI for the new polymers of the presentinvention is preferably greater than about 30 percent, especiallygreater than about 50 percent.

The most unique characteristic of the presently claimed polymers is ahighly unexpected flow property as shown in FIG. 2, where the I₁₀/I₂value is essentially independent of polydispersity index (i.e.M_(w)/M_(n)). This is contrasted with conventional polyethylene resinshaving rheological properties such that as the polydispersity indexincreases, the I₁₀/I₂ value also increases. Measurement of thepolydispersity index is done according to the following technique:

The polymers are analyzed by gel permeation chromatography (GPC) on aWaters 150 C high temperature chromatographic unit equipped wish threelinear mixed bed columns (Polymer Laboratories (10 micron particlesize)), operating at a system temperature of 140° C. The solvent is1,2,4-trichlorobenzene, from which about 0.5% by weight solutions of thesamples are prepared for injection. The flow rate is 1.0milliliter/minute and the injection size is 100 microliters.

The molecular weight determination is deduced by using narrow molecularweight distribution polystyrene standards (from Polymer Laboratories) inconjunction with their elution volumes. The equivalent polyethylenemolecular weights are determined by using appropriate Mark-Houwinkcoefficients for polyethylene and polystyrene (as described by Williamsand Word in Journal of Polymer Science, Polymer Letters, Vol. 6, (621)1968, incorporated herein by reference) to derive the equation:

M _(polyethylene)=(a)(M _(polystyrene))^(b)

In this equation, a=0.4316 and b=1.0. Weight average molecular weight,M_(w), is calculated in the usual manner according to the formula:

M _(w)=(R)(w _(i))(M _(i))

where w_(i) and M_(i) are the weight fraction and molecular weightrespectively of the ith fraction eluting from the GPC column.

Another highly unexpected characteristic of the polymers of the presentinvention is their non-susceptibility to melt fracture or the formationof extrudate defects during high pressure, high speed extrusion.Preferably polymers of the present invention do not experience“sharkskin” or surface melt fracture during the GER extrusion processeven at an extrusion pressure of 5000 psi and corresponding apparentstress of 4.3×10⁶ dyne/cm². In contrast, a conventional LLDPEexperiences “sharkskin” or onset of surface melt fracture (OSMF) at anapparent stress under comparable conditions as low as 1.0-1.4×10⁶dyne/cm².

Improvements of melt elasticity and processibility over conventionalLLDPE resins with similar MI are most pronounced when I₂ is lower thanabout 3 grams/10 minutes. Improvements of physical properties such asstrength properties, heat seal properties, and optical properties, overthe conventional LLDPE resins with similar MI, are most pronounced whenI₂ is lower than about 100 grams/10 minutes. The substantially linearpolymers of the present invention have processibility similar to that ofHigh Pressure LDPE while possessing strength and other physicalproperties similar to those of conventional LLDPE, without the benefitof special adhesion promoters (e.g., processing additives such as Viton™fluoroelastomers made by E. I. DuPont de Nemours & Company.

The improved melt elasticity and processibility of the substantiallylinear polymers according to the present invention result, it isbelieved, from their method of production. The polymers may be producedvia a continuous controlled polymerization process using at least onereactor, but can also be produced using multiple reactors (e.g., using amultiple reactor configuration as described in U.S. Pat. No. 3,914,342,incorporated herein by reference) at a polymerization temperature andpressure sufficient to produce the interpolymers having the desiredproperties. According to one embodiment of the present process, thepolymers are produced in a continuous process, as opposed to a batchprocess. Preferably, the polymerization temperature is from about 20° C.to about 250° C., using constrained geometry catalyst technology. If anarrow molecular weight distribution polymer (M_(w)/M_(n) of from about1.5 to about 2.5) having a higher I₁₀/I₂ ratio (e.g. I₁₀/I₂ of about 7or more, preferably at least about 8, especially at least about 9) isdesired, the ethylene concentration in the reactor is preferably notmore than about 8 percent by weight of the reactor contents, especiallynot more than about 4 percent by weight of the reactor contents.Preferably, the polymerization is performed in a solution polymerizationprocess. Generally, manipulation of I₁₀/I₂ while holding M_(w)/M_(n)relatively low for producing the novel polymers described herein is afunction of reactor temperature and/or ethylene concentration. Reducedethylene concentration and higher temperature generally produces higherI₁₀/I₂.

Suitable catalysts for use herein preferably include constrainedgeometry catalysts as disclosed in U.S. application Ser. Nos. 545,403,filed Jul. 3, 1990; 758,654, filed Sep. 12, 1991 now U.S. Pat. No.5,132,380; Ser. No. 758,660, filed Sep. 12, 1991, now abandoned; and720,041, filed Jun. 24, 1991, now abandoned the teachings of all ofwhich are incorporated herein by reference.

The monocyclopentadienyl transition metal olefin polymerizationcatalysts taught in U.S. Pat. No. 5,026,798, the teachings of which areincorporated herein by reference, are also suitable for use in preparingthe polymers of the present invention.

The foregoing catalysts may be further described as comprising a metalcoordination complex comprising a metal of groups 3-10 or the Lanthanideseries of the Periodic Table of the Elements and a delocalized n-bondedmoiety substituted with a constrain-inducing moiety, said complex havinga constrained geometry about the metal atom such that the angle at themetal between the centroid of the delocalized, substituted n-bondedmoiety and the center of at least one remaining substituent is less thansuch angle in a similar complex containing a similar n-bonded moietylacking in such constrain-inducing substituent, and provided furtherthat for such complexes comprising more than one delocalized,substituted n-bonded moiety, only one thereof for each metal atom of thecomplex is a cyclic, delocalized, substituted n-bonded moiety. Thecatalyst further comprises an activating cocatalyst.

Preferred catalyst complexes correspond to the formula:

wherein:

M is a metal of group 3-10, or the Lanthanide series of the PeriodicTable of the Elements;

Cp* is a cyclopentadienyl or substituted cyclopentadienyl group bound inan η⁵ bonding mode to M;

Z is a moiety comprising boron, or a member of group 14 of the PeriodicTable of the Elements, and optionally sulfur or oxygen, said moietyhaving up to 20 non-hydrogen atoms, and optionally Cp* and Z togetherform a fused ring system;

X independently each occurrence is an anionic ligand group or neutralLewis base ligand group having up to 30 non-hydrogen atoms;

n is 0, 1, 2, 3, or 4 and is 2 less than the valence of M; and

Y is an anionic or nonanionic ligand group bonded to Z and M comprisingnitrogen, phosphorus, oxygen or sulfur and having up to 20 non-hydrogenatoms, optionally Y and Z together form a fused ring system.

More preferably still, such complexes correspond to the formula:

wherein R′ each occurrence is independently selected from the groupconsisting of hydrogen, alkyl, aryl, silyl, germyl, cyano, halo andcombinations thereof having up to 20 non-hydrogen atoms;

X each occurrence independently is selected from the group consisting ofhydride, halo, alkyl, aryl, silyl, germyl, aryloxy, alkoxy, amide,siloxy, neutral Lewis base ligands and combinations thereof having up to20 non-hydrogen atoms;

Y is —O—, —S—, —NR*—, —PR*—, or a neutral two electron donor ligandselected from the group consisting of OR*, SR*, NR*₂, or PR*₂;

M is a previously defined; and

Z is SiR*₂, CR*₂, SiR*₂SiR*₂, CR*₂CR*₂, CR*═CR*, CR*₂SiR*₂, GeR*₂, BR*,BR*₂; wherein:

R* each occurrence is independently selected from the group consistingof hydrogen, alkyl, aryl, silyl, halogenated alkyl, halogenated arylgroups having up to 20 non-hydrogen atoms, and mixtures thereof, or twoor more R* groups from Y, Z, or both Y and Z form a fused ring system;and

n is 1 or 2.

It should be noted that whereas formula I and the following formulasindicate a cyclic structure for the catalysts, when Y is a neutral twoelectron donor ligand, the bond between M and Y is more accuratelyreferred to as a coordinate-covalent bond. Also, it should be noted thatthe complex may exist as a dimer or higher oligomer.

Further preferably, at least one of R′, Z, or R* is an electron donatingmoiety. Thus, highly preferably Y is a nitrogen or phosphorus containinggroup corresponding to the formula —N(R″— or —P(R″)—, wherein R″ isC₁₋₁₀ alkyl or aryl, ie. an amido or phosphido group.

Most highly preferred complex compounds are amidosilane- oramidoalkanediyl-compounds corresponding to the formula:

wherein:

M is titanium, zirconium or hafnium, bound in an η⁵ bonding mode to thecyclopentadienyl group;

R′ each occurrence is independently selected from the group consistingof hydrogen, silyl, alkyl, aryl and combinations thereof having up to 10carbon or silicon atoms;

E is silicon or carbon;

X independently each occurrence is hydride, halo, alkyl, aryl, aryloxyor alkoxy of up to 10 carbons;

m is 1 or 2; and

n is 1 or 2.

Examples of the above most highly preferred metal coordination compoundsinclude compounds wherein the R′ on the amido group is methyl, ethyl,propyl, butyl, pentyl, hexyl, (including isomers), norbornyl, benzyl,phenyl, etc.; the cyclopentadienyl group is cyclopentadienyl, indenyl,tetrahydroindenyl, fluorenyl, octahydrofluorenyl, etc.; R′ on theforegoing cyclopentadienyl groups each occurrence is hydrogen, methyl,ethyl, propyl, butyl, pentyl, hexyl, (including isomers), norbornyl,benzyl, phenyl, etc.; and X is chloro, bromo, iodo, methyl, ethyl,propyl, butyl, pentyl, hexyl, (including isomers), norbornyl, benzyl,phenyl, etc. Specific compounds include:(tert-butylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediylzirconiumdichloride,(tert-butylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediyltitaniumdichloride,(methylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediylzirconiumdichloride,(methylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediyltitaniumdichloride,(ethylamido)(tetramethyl-η⁵-cyclopentadienyl)-methylenetitaniumdichloro, (tert-butylamido)dibenzyl(tetramethyl-η⁵-cyclopentadienyl)silanezirconium dibenzyl,(benzylamido)dimethyl(tetramethyl-η⁵-cyclopentadienyl)silanetitaniumdichloride,(phenylphosphido)dimethyl(tetramethyl-η⁵-cyclopentadienyl)silanezirconiumdibenzyl,(tert-butylamido)dimethyl(tetramethyl-η⁵-cyclopentadienyl)silanetitaniumdimethyl, and the like.

The complexes may be prepared by contacting a derivative of a metal, M,and a group I metal derivative or Grignard derivative of thecyclopentadienyl compound in a solvent and separating the saltbyproduct. Suitable solvents for use in preparing the metal complexesare aliphatic or aromatic liquids such as cyclohexane,methylcyclohexane, pentane, hexane, heptane, tetrahydrofuran, diethylether, benzene, toluene, xylene, ethylbenzene, etc., or mixturesthereof.

In a preferred embodiment, the metal compound is MX_(n+1), i.e. M is ina lower oxidation state than in the corresponding compound, MX_(n+2) andthe oxidation state of M in the desired final complex. A noninterferingoxidizing agent may thereafter be employed to raise the oxidation stateof the metal. The oxidation is accomplished merely by contacting thereactants utilizing solvents and reaction conditions used in thepreparation of the complex itself. By the term “noninterfering oxidizingagent” is meant a compound having an oxidation potential sufficient toraise the metal oxidation state without interfering with the desiredcomplex formation or subsequent polymerization processes. A particularlysuitable noninterfering oxidizing agent is AgCl or an organic halidesuch as methylene chloride. The foregoing techniques are disclosed inU.S. Ser. Nos. 545,403, filed Jul. 3, 1990 and 702,475, filed May 20,1991, now abandoned, the teachings of both of which are incorporatedherein by reference.

Additionally the complexes may be prepared according to the teachings ofthe copending application Ser. No. 07/778,433 entitled: “Preparation ofMetal Coordination Complex (I)”, filed in the names of Peter Nickias andDavid Wilson, on Oct. 15, 1991, now abandoned, and the copendingapplication Ser. No. 07/778,432 entitled: “Preparation of MetalCoordination Complex (II)”, filed in the names of Peter Nickias andDavid Devore, on Oct. 15, 1991, now abandoned, the teachings of whichare incorporated herein by reference thereto.

Suitable cocatalysts for use herein include polymeric or oligomericalumoxanes, especially methyl alumoxane, as well as inert, compatible,noncoordinating, ion forming compounds. Preferred cocatalysts are inert,noncoordinating, boron compounds.

Ionic active catalyst species which can be used to polymerize thepolymers described herein correspond to the formula:

wherein:

M is a metal of group 3-10, or the Lanthanide series of the PeriodicTable of the Elements;

Cp* is a cyclopentadienyl or substituted cyclopentadienyl group bound inan η⁵ bonding mode to M;

Z is a moiety comprising boron, or a member of group 14 of the PeriodicTable of the Elements, and optionally sulfur or oxygen, said moietyhaving up to 20 non-hydrogen atoms, and optionally Cp* and Z togetherform a fused ring system;

X independently each occurrence is an anionic ligand group or neutralLewis base ligand group having up to 30 non-hydrogen atoms;

n is 0, 1, 2, 3, or 4 and is 2 less than the valence of M; and

A⁻ is a noncoordinating compatible anion.

One method of making the ionic catalyst species which can be utilized tomake the polymers of the present invention involve combining:

a) at least one first component which is a mono(cyclopentadienyl)derivative of a metal of Group 3-10 or the Lanthanide Series of thePeriodic Table of the Elements containing at least one substituent whichwill combine with the cation of a second component (describedhereinafter) which first component is capable of forming a cationformally having a coordination number that is one less than its valence,and

b) at least one second component which is a salt of a Bronsted acid anda noncoordinating, compatible anion.

More particularly the noncoordinating, compatible anion of the Bronstedacid salt may comprise a single coordination complex comprising acharge-bearing metal or metalloid core, which anion is both bulky andnon-nucleophilic. The recitation “metalloid”, as used herein, includesnon-metals such as boron, phosphorus and the like which exhibitsemi-metallic characteristics.

Illustrative, but not limiting examples of monocyclopentadienyl metalcomponents (first components) which may be used in the preparation ofcationic complexes are derivatives of titanium, zirconium, hafnium,chromium, lanthanum, etc. Preferred components are titanium or zirconiumcompounds. Examples of suitable monocyclopentadienyl metal compounds arehydrocarbyl-substituted monocyclopentadienyl metal compounds such as(tert-butylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediylzirconiumdimethyl,(tert-butylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediyltitaniumdimethyl,(methylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediylzirconiumdibenzyl,(methylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediyltitaniumdimethyl,(ethylamido)(tetramethyl-η⁵-cyclopentadienyl)-methylenetitaniumdimethyl, (tert-butylamido)dibenzyl(tetramethyl-η⁵-cyclopentadienyl)silanezirconium dibenzyl,(benzylamido)dimethyl(tetramethyl-η⁵-cyclopentadienyl)silanetitaniumdiphenyl,(phenylphosphido)dimethyl(tetramethyl-η⁵-cyclopentadienyl)silanezirconiumdibenzyl, and the like.

Such components are readily prepared by combining the correspondingmetal chloride with a dilithium salt of the substituted cyclopentadienylgroup such as a cyclopentadienyl-alkanediyl, cyclopentadienyl-silaneamide, or cyclopentadienyl-phosphide compound. The reaction is conductedin an inert liquid such as tetrahydrofuran, C₅₋₁₀ alkanes, toluene, etc.utilizing conventional synthetic procedures. Additionally, the firstcomponents may be prepared by reaction of a group II derivative of thecyclopentadienyl compound in a solvent and separating the saltby-product. Magnesium derivatives of the cyclopentadienyl compounds arepreferred. The reaction may be conducted in an inert solvent such ascyclohexane, pentane, tetrahydrofuran, diethyl ether, benzene, toluene,or mixtures of the like. The resulting metal cyclopentadienyl halidecomplexes may be alkylated using a variety of techniques. Generally, themetal cyclopentadienyl alkyl or aryl complexes may be prepared byalkylation of the metal cyclopentadienyl halide complexes with alkyl oraryl derivatives of group I or group II metals. Preferred alkylatingagents are alkyl lithium and Grignard derivatives using conventionalsynthetic techniques. The reaction may be conducted in an inert solventsuch as cyclohexane, pentane, tetrahydrofuran, diethyl ether, benzene,toluene, or mixtures of the like. A preferred solvent is a mixture oftoluene and tetrahydrofuran.

Compounds useful as a second component in the preparation of the ioniccatalysts useful in this invention will comprise a cation, which is aBronsted acid capable of donating a proton, and a compatiblenoncoordinating anion. Preferred anions are those containing a singlecoordination complex comprising a charge-bearing metal or metalloid corewhich anion is relatively large (bulky), capable of stabilizing theactive catalyst species (the Group 3-10 or Lanthanide Series cation)which is formed when the two components are combined and sufficientlylabile to be displaced by olefinic, diolefinic and acetylenicallyunsaturated substrates or other neutral Lewis bases such as ethers,nitrites and the like. Suitable metals, then, include, but are notlimited to, aluminum, gold, platinum and the like. Suitable metalloidsinclude, but are not limited to, boron, phosphorus, silicon and thelike. Compounds containing anions which comprise coordination complexescontaining a single metal or metalloid atom are, of course, well knownand many, particularly such compounds containing a single boron atom inthe anion portion, are available commercially. In light of this, saltscontaining anions comprising a coordination complex containing a singleboron atom are preferred.

Highly preferably, the second component useful in the preparation of thecatalysts of this invention may be represented by the following generalformula:

(L-H)⁺ [A] ⁻

wherein:

L is a neutral Lewis base;

(L-H)⁺ is a Bronsted acid; and

[A]⁻ is a compatible, noncoordinating anion.

More preferably [A]⁻ corresponds to the formula:

[M′Q _(q)]⁻

wherein:

M′ is a metal or metalloid selected from Groups 5-15 of the PeriodicTable of the Elements; and

Q independently each occurrence is selected from the Group consisting ofhydride, dialkylamido, halide, alkoxide, aryloxide, hydrocarbyl, andsubstituted-hydrocarbyl radicals of up to 20 carbons with the provisothat in not more than one occurrence is Q halide and

q is one more than the valence of M′.

Second components comprising boron which are particularly useful in thepreparation of catalysts of this invention may be represented by thefollowing general formula:

[L-H] ⁺ [BQ ₄]⁻

wherein:

L is a neutral Lewis base;

[L-H]⁺ is a Bronsted acid;

B is boron in a valence state of 3; and

Q is as previously defined.

Illustrative, but not limiting, examples of boron compounds which may beused as a second component in the preparation of the improved catalystsof this invention are trialkyl-substituted ammonium salts such astriethylammonium tetraphenylborate, tripropylammonium tetraphenylborate,tri(n-butyl)ammonium tetraphenylborate, trimethylammoniumtetra(p-tolylborate), tributylammonium tetrakis-pentafluorophenylborate,tripropylammonium tetrakis-2,4-dimethylphenylborate, tributylammoniumtetrakis-3,5-dimethylphenylborate, triethylammoniumtetrakis-(3,5-di-trifluoromethylphenyl)borate and the like. Alsosuitable are N,N-dialkyl anilinium salts such as N,N-dimethylaniliniumtetraphenylborate, N,N-diethylanilinium tetraphenylborate,N,N-2,4,6-pentamethylanilinium tetraphenylborate and the like; dialkylammonium salts such as di-(i-propyl)ammoniumtetrakis-pentafluorophenylborate, dicyclohexylammonium tetraphenylborateand the like; and triaryl phosphonium salts such as triphenylphosphoniumtetraphenylborate, tri(methylphenyl)phosphoniumtetrakis-pentafluorophenylborate, tri(dimethylphenyl)phosphoniumtetraphenylborate and the like.

Preferred ionic catalysts are those having a limiting charge separatedstructure corresponding to the formula:

wherein:

M is a metal of group 3-10, or the Lanthanide series of the PeriodicTable of the Elements;

Cp* is a cyclopentadienyl or substituted cyclopentadienyl group bound inan η⁵ bonding mode to M;

Z is a moiety comprising boron, or a member of group 14 of the PeriodicTable of the Elements, and optionally sulfur or oxygen, said moietyhaving up to 20 non-hydrogen atoms, and optionally Cp* and Z togetherform a fused ring system;

X independently each occurrence is an anionic ligand group or neutralLewis base ligand group having up to 30 non-hydrogen atoms;

n is 0, 1, 2, 3, or 4 and is 2 less than the valence of M; and

XA*⁻ is ⁻XB(C₆F₅)₃.

This class of cationic complexes may be conveniently prepared bycontacting a metal compound corresponding to the formula:

wherein:

Cp, M, and n are as previously defined,

with tris(pentafluorophenyl)borane cocatalyst under conditions to causeabstraction of X and formation of the anion ⁻XB(C₆F₅)₃.

Preferably X in the foregoing ionic catalyst is C₁-C₁₀ hydrocarbyl, mostpreferably methyl.

The preceding formula is referred to as the limiting, charge, separatedstructure. However, it is to be understood that, particularly in solidform, the catalyst may not be fully charge separated. That is, the Xgroup may retain a partial covalent bond to the metal atom, M. Thus, thecatalysts may be alternately depicted as possessing the formula:

The catalysts are preferably prepared by contacting the derivative of aGroup 4 or Lanthanide metal with the tris(pentafluorophenylborane in aninert diluent such as an organic liquid. Tris(pentafluorphenyl)borane isa commonly available Lewis acid that may be readly prepared according toknown techniques. The compound is disclosed in Marks, et al. J. Am.Chem. Soc. 1991, 113, 3623-3625 for use in alkyl abstraction ofzirconocenes.

All reference to the Periodic Table of the Elements herein shall referto the Periodic Table of the Elements, published and copyrighted by CRCPress, Inc., 1989. Also, any reference to a Group or Groups shall be tothe Group or Groups as reflected in this Periodic Table of the Elementsusing the IUPAC system for numbering groups.

It is believed that in the constrained geometry catalysts used hereinthe metal atom is forced to greater exposure of the active metal sitebecause one or more substituents on the single cyclopentadienyl orsubstituted cyclopentadienyl group forms a portion of a ring structureincluding the metal atom, wherein the metal is both bonded to anadjacent covalent moiety and held in association with thecyclopentadienyl group through an η⁵ or other n-bonding interaction. Itis understood that each respective bond between the metal atom and theconstituent atoms of the cyclopentadienyl or substitutedcyclopentadienyl group need not be equivalent. That is, the metal may besymmetrically or unsymmetrically n-bound to the cyclopentadienyl orsubstituted cyclopentadienyl group.

The geometry of the active metal site is further defined as follows. Thecentroid of the cyclopentadienyl or substituted cyclopentadienyl groupmay be defined as the average of the respective X, Y, and Z coordinatesof the atomic centers forming the cyclopentadienyl or substitutedcyclopentadienyl group. The angle, θ, formed at the metal center betweenthe centroid of the cyclopentadienyl or substituted cyclopentadienylgroup and each other ligand of the metal complex may be easilycalculated by standard techniques of single crystal X-ray diffraction.Each of these angles may increase or decrease depending on the molecularstructure of the constrained geometry metal complex. Those complexeswherein one or more of the angles, θ, is less than in a similar,comparative complex differing only in the fact that theconstrain-inducing substituent is replaced by hydrogen have constrainedgeometry for purposes of the present invention. Preferably one or moreof the above angles, θ, decrease by at least 5 percent, more preferably7.5 percent, compared to the comparative complex. Highly preferably, theaverage value of all bond angles, θ, is also less than in thecomparative complex.

Preferably, monocyclopentadienyl metal coordination complexes of group 4or lanthanide metals according to the present invention have constrainedgeometry such that the smallest angle, θ, is less than 115°, morepreferably less than 110°, most preferably less than 105°.

Other compounds which are useful in the catalyst compositions of thisinvention, especially compounds containing other Group 4 or Lanthanidemetals, will, of course, be apparent to those skilled in the art.

In general, the polymerization according to the present invention may beaccomplished at conditions well known in the prior art for Ziegler-Nattaor Kaminsky-Sinn type polymerization reactions, that is, temperaturesfrom 0 to 250° C. and pressures from atmospheric to 1000 atmospheres(100 MPa). Suspension, solution, slurry, gas phase or other processconditions may be employed if desired. A support may be employed butpreferably the catalysts are used in a homogeneous manner. It will, ofcourse, be appreciated that the active catalyst system, especiallynonionic catalysts, form in situ if the catalyst and the cocatalystcomponents thereof are added directly to the polymerization process anda suitable solvent or diluent, including condensed monomer, is used insaid polymerization process. It is, however, preferred to form theactive catalyst in a separate step in a suitable solvent prior to addingthe same to the polymerization mixture.

The polymerization conditions for manufacturing the polymers of thepresent invention are generally those useful in the solutionpolymerization process, although the application of the presentinvention is not limited thereto. Gas phase polymerization processes arealso believed to be useful, provided the proper catalysts andpolymerization conditions are employed.

Fabricated articles made from the novel olefin polymers may be preparedusing all of the conventional polyolefin processing techniques. Usefularticles include films (e.g., cast, blown and extrusion coated), fibers(e.g., staple fibers (including use of a novel olefin polymer disclosedherein as at least one component comprising at least a portion of thefiber's surface), spunbond fibers or melt blown fibers (using, e.g.,systems as disclosed in U.S. Pat. No. 4,340,563, U.S. Pat. No.4,663,220, U.S. Pat. No. 4,668,566, or U.S. Pat. No. 4,322,027, all ofwhich are incorporated herein by reference), and gel spun fibers (e.g.,the system disclosed in U.S. Pat. No. 4,413,110, incorporated herein byreference)), both woven and nonwoven fabrics (e.g., spunlaced fabricsdisclosed in U.S. Pat. No. 3,485,706, incorporated herein by reference)or structures made from such fibers (including, e.g., blends of thesefibers with other fibers, e.g., PET or cotton) and molded articles(e.g., made using an injection molding process, a blow molding processor a rotomolding process). The new polymers described herein are alsouseful for wire and cable coating operations, as well as in sheetextrusion for vacuum forming operations.

Useful compositions are also suitably prepared comprising thesubstantially linear polymers of the present invention and at least oneother natural or synthetic polymer. Preferred other polymers includethermoplastics such as styrene-butadiene block copolymers, polystyrene(including high impact polystyrene), ethylene vinyl alcohol copolymers,ethylene acrylic acid copolymers, other olefin copolymers (especiallypolyethylene copolymers) and homopolymers (e.g., those made usingconventional heterogeneous catalysts). Examples include polymers made bythe process of U.S. Pat. No. 4,076,698, incorporated herein byreference, other linear or substantially linear polymers of the presentinvention, and mixtures thereof. Other substantially linear polymers ofthe present invention and conventional HDPE and/or LLDPE are preferredfor use in the thermoplastic compositions.

Compositions comprising the olefin polymers can also be formed intofabricated articles such as those previously mentioned usingconventional polyolefin processing techniques which are well known tothose skilled in the art of polyolefin processing.

All procedures were performed under an inert atmosphere or nitrogen orargon. Solvent choices were often optional, for example, in most caseseither pentane or 30-60 petroleum ether can be interchanged. Amines,silanes, lithium reagents, and Grignard reagents were purchased fromAldrich Chemical Company. Published methods for preparingtetramethylcyclopentadiene (C₅Me₄H₂) and lithiumtetramethylcyclopentadienide (Li(C₅Me₄H)) include C. M. Fendrick et al.Organometallics, 3, 819 (1984). Lithiated substituted cyclopentadienylcompounds may be typically prepared from the correspondingcyclopentadiene and a lithium reagent such as n-butyl lithium. Titaniumtrichloride (TiCl₃) was purchased from Aldrich Chemical Company. Thetetrahydrofuran adduct of titanium trichloride, TiCl₃(THF)₃, wasprepared by refluxing TiCl₃ in THF overnight, cooling, and isolating theblue solid product, according to the procedure of L. E. Manzer, Inorg.Syn., 21, 135 (1982).

EXAMPLES 1-4

The metal complex solution for Example 1 is prepared as follows:

Part 1: Prep of Li(C₅Me₄H)

In the drybox, a 3 L 3-necked flask was charged with 18.34 g of C₅Me₄H₂,800 mL of pentane, and 500 mL of ether. The flask was topped with areflux condenser, a mechanical stirrer, and a constant addition funnelcontainer 63 mL of 2.5 M n-BuLi in hexane. The BuLi was added dropwiseover several hours. A very thick precipitate formed: approx. 1000 mL ofadditional pentane had to be added over the course of the reaction toallow stirring to continue. After the addition was complete, the mixturewas stirred overnight. The next day, the material was filtered, and thesolid was thoroughly washed with pentane and then dried under reducedpressure. 14.89 g of Li(C₅Me₄H) was obtained (78 percent).

Part 2: Prep of C₅Me₄HSiMe₂Cl

In the drybox 30.0 g of Li(C₅Me₄H) was placed in a 500 mL Schlenk flaskwith 250 mL of THF and a large magnetic stir bar. A syringe was chargedwith 30 mL of Me₂SiCl₂ and the flask and syringe were removed from thedrybox. On the Schlenk line under a flow of argon, the flask was cooledto −78° C., and the Me₂SiCl₂ added in one rapid addition. The reactionwas allowed to slowly warm to room temperature and stirred overnight.The next morning the volatile materials were removed under reducedpressure, and the flask was taken into the drybox. The oily material wasextracted with pentane, filtered, and the pentane was removed underreduced pressure to leave the C₅Me₄HSiMe₂Cl as a clear yellow liquid(46.83 g; 92.9 percent).

Part 3: Prep of C₅Me₄HSiMe₂NH^(t)Bu

In the drybox, a 3-necked 2 L flask was charged with 37.4 g oft-butylamine and 210 mL of THF. C₅Me₄HSiMe₂Cl (25.47 g) was slowlydripped into the solution over 3-4 hours. The solution turned cloudy andyellow. The mixture was stirred overnight and the volatile materialsremoved under reduced pressure. The residue was extracted with diethylether, the solution was filtered, and the ether removed under reducedpressure to leave the C₅Me₄HSiMe₂NH^(t)Bu as a clear yellow liquid(26.96 g; 90.8 percent).

Part 4: Prep of [MgCl]₂[Me₄C₅SiMe₂N^(t)Bu](THF)_(x)

In the drybox, 14.0 mL of 2.0 M isopropylmagnesium chloride in ether wassyringed into a 250 mL flask. The ether was removed under reducedpressure to leave a colorless oil. 50 mL of a 4:1 (by volume)toluene:THF mixture was added followed by 3.50 g of Me₄HC₅SiMe₂NH^(t)Bu.The solution was heated to reflux. After refluxing for 2 days, thesolution was cooled and the volatile materials removed under reducedpressure. The white solid residue was slurried in pentane and filteredto leave a white powder, which was washed with pentane and dried underreduced pressure. The white powder was identified as[MgCl]₂[Me₄C₅SiMe₂N^(t)Bu](THF)_(x) (yield: 6.7 g).

Part 5: Prep of [C₅Me₄₍SiMe₂N^(t)Bu)]TiCl₂

In the drybox, 0.50 g of TiCl₃(THF)₃ was suspended in 10 mL of THF. 0.69g of solid [MgCl]₂[Me₄C₅SiMe₂N^(t)Bu](THF)_(x) was added, resulting in acolor change from pale blue to deep purple. After 15 minutes, 0.35 g ofAgCl was added to the solution. The color immediately began to lightento a pale green-yellow. After 1½ hours, the THF was removed underreduced pressure to leave a yellow-green solid. Toluene (20 mL) wasadded, the solution was filtered, and the toluene was removed underreduced pressure to leave a yellow-green solid, 0.51 g (quantitativeyield) identified by 1H NMR as [C₅Me₄(SiMe₂N^(t)Bu)]TiCl₂.

Part 6: Preparation of [C₅Me₄(SiMe₂N^(t)Bu)]TiMe₂

In an inert atmosphere glove box, 9.031 g of [C₅Me₄(Me₂SiN^(t)Bu)]TiCl₂is charged into a 250 ml flask and dissolved into 100 ml of THF. Thissolution is cooled to about −25° C. by placement in the glove boxfreezer for 15 minutes. To the cooled solution is added 35 ml of a 1.4 MMeMgBr solution in toluene/THF (75/25). The reaction mixture is stirredfor 20 to 25 minutes followed by removal of the solvent under vacuum.The resulting solid is dried under vacuum for several hours. The productis extracted with pentane (4×50 ml) and filtered. The filtrate iscombined and the pentane removed under vacuum giving the catalyst as astraw yellow solid.

The metal complex, [C₅Me₄(SiMe₂N^(t)Bu)]TiMe₂, solution for Examples 2and 3 is prepared as follows:

In an inert atmosphere glove box 10.6769 g of a tetrahydrofuran adductof titanium trichloride, TiCl₃(THF)₃, is loaded into a 1 l flask andslurried into ≈300 ml of THF. To this slurry, at room temperature, isadded 17.402 g of [MgCl]₂ [N^(t)BuSiMe₂C₅Me₄] (THF)_(x) as a solid. Anadditional 200 ml of THF is used to help wash this solid into thereaction flask. This addition resulted in an immediate reaction giving adeep purple solution. After stirring for 5 minutes 9.23 ml of a 1.56 Msolution of CH₂Cl₂ in THF is added giving a quick color change to darkyellow. This stage of the reaction is allowed to stir for about 20 to 30minutes. Next, 61.8 ml of a 1.4 M MeMgBr solution in toluene/THF(75/25)is added via syringe. After about 20 to 30 minutes stirring time thesolvent is removed under vacuum and the solid dried. The product isextracted with pentane (8×50 ml) and filtered. The filtrate is combinedand the pentane removed under vacuum giving the metal complex as a tansolid.

The metal complex, [C₅Me₄(SiMe₂N^(t)Bu)]TiMe₂, solution for Example 4 isprepared as follows:

In an inert atmosphere glove box 4.8108 g of TiCl₃(thf)₃ is placed in a500 ml flask and slurried into 130 ml of THF. In a separate flask 8.000g of [MgCl]₂[N^(t)BuSiMe₂C₅Me₄](THF)_(x) is dissolved into 150 ml ofTHF. These flasks are removed from the glove box and attached to avacuum line and the contents cooled to −30° C. The THF solution of[MgCl]₂[N^(t)BuSiMe₂C₅Me₄](THF)_(x) is transferred (over a 15 minuteperiod) via cannula to the flask containing the TiCl₃(THF)₃ slurry. Thisreaction is allowed to stir for 1.5 hours over which time thetemperature warmed to 0° C. and the solution color turned deep purple.The reaction mixture is cooled back to −30° C. and 4.16 ml of a 1.56 MCH₂Cl₂ solution in THF is added. This stage of the reaction is stirredfor an additional 1.5 hours and the temperature warmed to −10° C. Next,the reaction mixture is again cooled to −40° C. and 27.81 ml of a 1.4 MMeMgBr solution in toluene/THF (75/25) was added via syringe and thereaction is now allowed to warm slowly to room temperature over 3 hours.After this time the solvent is removed under vacuum and the solid dried.At this point the reaction flask is brought back into the glove boxwhere the product is extracted with pentane (4×50 ml) and filtered. Thefiltrate is combined and the pentane removed under vacuum giving thecatalyst as a tan solid. The metal complex is then dissolved into amixture of C₈-C₁₀ saturated hydrocarbons (e.g., Isopar® E, made byExxon) and ready for use in polymerization.

Polymerization

The polymer products of Examples 1-4 are produced in a solutionpolymerization process using a continuously stirred reactor. Additives(e.g., antioxidants, pigments, etc.) can be incorporated into theinterpolymer products either during the pelletization step or aftermanufacture, with a subsequent re-extrusion. Examples 1-4 are eachstabilized with 1250 ppm Calcium Stearate, 200 ppm Irgonox 1010, and1600 ppm Irgafos 168. Irgafos™ 168 is a phosphite stabilizer andIrgonox™ 1010 is a hindered polyphenol stabilizer (e.g., tetrakis[methylene 3-(3,5-ditert.butyl-4-hydroxy-phenylpropionate)]methane. Bothare trademarks of and made by Ciba-Geigy Corporation. A representativeschematic for the polymerization process is shown in FIG. 1.

The ethylene (4) and the hydrogen (5) are combined into one stream (15)before being introduced into the diluent mixture (3). Typically, thediluent mixture comprises a mixture of C₈-C₁₀ saturated hydrocarbons(1), (e.g., Isopar® E, made by Exxon) and the comonomer(s) (2). Forexamples 1-4, the comonomer is 1-octene. The reactor feed mixture (6) iscontinuously injected into the reactor (9). The metal complex (7) andthe cocatalyst (8) (the cocatalyst is tris(pentafluorophenyl)borane forExamples 1-4 herein which forms the ionic catalyst insitu) are combinedinto a single stream and also continuously injected into the reactor.Sufficient residence time is allowed for the metal complex andcocatalyst to react to the desired extent for use in the polymerizationreactions, at least about 10 seconds. For the polymerization reactionsof Examples 1-4, the reactor pressure is held constant at about 490psig. Ethylene content of the reactor, after reaching steady state, ismaintained below about 8 percent.

After polymerization, the reactor exit stream (14) is introduced into aseparator (10) where the molten polymer is separated from the unreactedcomonomer(s), unreacted ethylene, unreacted hydrogen, and diluentmixture stream (13). The molten polymer is subsequently strand choppedor pelletized and, after being cooled in a water bath or pelletizer(11), the solid pellets are collected (12). Table I describes thepolymerization conditions and the resultant polymer properties:

TABLE I Example 1 2 3 4 Ethylene feed rate 3.2 3.8 3.8 3.8 (lbs/hour)Comonomer/Olefin* 12.3 0 0 0 ratio (mole %) Hydrogen/ 0.054 0.072 0.0830.019 Ethylene ratio (mole %) Diluent/ 9.5 7.4 8.7 8.7 Ethylene ratio(weight basis) metal 0.00025 0.0005 0.001 0.001 complex concentration(molar) metal 5.9 1.7 2.4 4.8 complex flow rate (ml/min) cocatalyst0.001 0.001 0.002 0.002 concentration (molar) cocatalyst 2.9 1.3 6 11.9flow rate (ml/min) Reactor 114 160 160 200 temperature (° C.) Ethylene2.65 3.59 0.86 1.98 Conc. in the reactor exit stream (weight percent)Product I₂ 1.22 0.96 1.18 0.25 (g/10 minutes) Product density 0.9030.954 0.954 0.953 (g/cc) Product I₁₀/I₂ 6.5 7.4 11.8 16.1 Product 1.861.95 2.09 2.07 M_(w)/M_(n) *For Examples 1-4, the Comonomer/Olefin ratiois defined as the percentage molar ratio of ((1-octene + ethylene))

The ¹³C NMR spectrum of Example 3 (ethylene homopolymer) shows peakswhich can be assigned to the αδ+, βδ+, and methine carbons associatedwith a long chain branch. Long chain branching is determined using themethod of Randall described earlier in this disclosure, wherein hestates that “Detection of these resonances in high-density polyethyleneswhere no 1-olefins were added during the polymerization should bestrongly indicative of the presence of long chain branching.” Using theequation 141 from Randall (p. 292):

Branches per 10,000 carbons=[⅓α/T _(Tot))]×10⁴,

wherein α=the average intensity of a carbon from a branch (αδ+) carbonand T_(Tot)=the total carbon intensity,

the number of long chain branches in this sample is determined to be 3.4per 10,000 carbon atoms, or 0.34 long chain branches/1000 carbon atoms.

EXAMPLES 5, 6 AND COMPARATIVE EXAMPLES 7-9

Examples 5, 6 and comparison examples 7-9 with the same melt index aretested for rheology comparison. Examples 5 and 6 are the substantiallylinear polyethylenes produced by the constrained geometry catalysttechnology, as described in Examples 1-4. Examples 5 and 6 are stablizedas Examples 1-4.

Comparison examples 7, 8 and 9 are conventional heterogeneous Zieglerpolymerization blown film resins Dowlex® 2045A, Attane® 4201, andAttane® 4403, respectively, all of which are ethylene/1-octenecopolymers made by The Dow Chemical Company.

Comparative example 7 is stablized with 200 ppm Irgonox® 1010, and 1600ppm Irgafos® 168 while comparative examples 8 and 9 are stablized with200 ppm Irgonox® 1010 and 800 ppm PEPQ®. PEPQ® is a trademark of SandozChemical, the primary ingredient of which is believed to betetrakis-(2,4-di-tertbutyl-phenyl)-4,4′biphenylphosphonite.

A comparison of the physical properties of each example and comparativeexample is listed in Table II.

TABLE II Compar- Compar- Example Example ison ison Comparison Property 56 Example 7 Example 8 Example 9 I₂ 1 1 1 1 0.76 density .92 .902 .92.912 .905 I₁₀/I₂ 9.45 7.61 7.8-8 8.2 8.7 M_(w)/M_(n) 1.97 2.09 3.5-3.83.8 3.8-4.0

Surprisingly, even though the molecular weight distribution of Examples5 and 6 is narrow (i.e., M_(w)/M_(n) is low), the I₁₀/I₂ values arehigher in comparison with comparative examples 7-9. A comparison of therelationship between I₁₀/I₂ vs. M_(w)/M_(n) for some of the novelpolymers described herein and conventional heterogeneous Zieglerpolymers is given in FIG. 2. The I₁₀/I₂ value for the novel polymers ofthe present invention is essentially independent of the molecular weightdistribution, M_(w)/M_(n), which is not true for conventional Zieglerpolymerized resins.

Example 5 and comparison example 7 with similar melt index and density(Table II) are also extruded via a Gas Extrusion Rheometer (GER) at 190°C. using a 0.0296″ diameter, 20 L/D die. The processing index (P.I.) ismeasured at an apparent shear stress of 2.5×10⁶ dyne/cm² as describedpreviously. The onset of gross melt fracture can easily be identifiedfrom the shear stress vs. shear rate plot shown in FIG. 3 where a suddenjump of shear rate occurs. A comparison of the shear stresses andcorresponding shear rates before the onset of gross melt fracture islisted in Table III. It is particularly interesting that the PI ofExample 5 is more than 20% lower than the PI of comparative example 7and that the onset of melt fracture or sharkskin for Example 5 is alsoat a significantly higher shear stress and shear rate in comparison withthe comparative example 7. Furthermore, the Melt Tension (MT) as well asElastic Modulus of Example 5 are higher than that of comparative example7.

TABLE III Comparison Property Example 5 example 7 I₂ 1 1 I₁₀/I₂ 9.457.8-8 PI, kpoise 11 15 Melt Tension 1.89 1.21 Elastic Modulus 2425 882.6@.1 rad/sec (dyne/cm²) OGMF*, critical >1556 (not 936 shear rate (1/sec)observed) OGMF*, critical .452 .366 shear stress (MPa) OSMF**,critical >1566 (not ˜628 shear rate (1/sec.) observed) OSMF**, critical˜0.452 ˜0.25 shear stress (MPa) *Onset of Gross Melt Fracture. **Onsetof Surface Melt Fracture.

Example 6 and comparison example 9 have similar melt index and density,but example 6 has lower I₁₀/I₂ (Table IV). These polymers are extrudedvia a Gas Extrusion Rheometer (GER) at 190° C. using a 0.0296 inchdiameter, 20:1 L/D die. The processing index (PI) is measured at anapparent shear stress of 2.15×10⁶ dyne/cm² as described previously.

TABLE IV Comparison Property Example 6 example 9 I₂ (g/10 minutes) 10.76 I₁₀/I₂ 7.61 8.7 PI (kpoise) 14 15 Melt Tension (g) 1.46 1.39Elastic Modulus 1481 1921 @0.1 rad/sec (dyne/cm2) OGMF*, critical 1186652 shear rate (1/sec) OGMF*, critical 0.431 0.323 shear stress (MPa)OSMF*, critical ˜764 ˜402 shear rate (1/sec.) OSMF**, critical 0.3660.280 shear stress (MPa) *Onset of Gross Melt Fracture. **Onset ofSurface Melt Fracture.

The onset of gross melt fracture can easily be identified from the shearstress vs. shear rate plot shown in FIG. 4 where a sudden increase ofshear rate occurs at an apparent shear stress of about 3.23×10⁶ dyne/cm²(0.323 MPa). A comparison of the shear stresses and corresponding shearrates before the onset of gross melt fracture is listed in Table IV. ThePI of Example 6 is surprisingly about the same as comparative example 9,even though the I₁₀/I₂ is lower for Example 6. The onset of meltfracture or sharkskin for Example 6 is also at a significantly highershear stress and shear rate in comparison with the comparative example9. Furthermore, it is also unexpected that the Melt Tension (MT) ofExample 6 is higher than that of comparative example 9, even though themelt index for Example 6 is slightly higher and the I₁₀/I₂ is slightlylower than that of comparative example 9.

EXAMPLE 10 AND COMPARATIVE EXAMPLE 11

Blown film is fabricated from two novel ethylene/1-octene polymers madein accordance with the present invention and from two comparativeconventional polymers made according to conventional Ziegler catalysis.The blown films are tested for physical properties, including heat sealstrength versus heat seal temperature (shown in FIG. 5 for Examples 10and 12 and comparative examples 11 and 13), machine (MD) and crossdirection (CD) properties (e.g., tensile yield and break, elongation atbreak and Young's modulus). Other film properties such as dart,puncture, tear, clarity, haze, 20 degree gloss and block are alsotested.

Blown Film Fabrication Conditions

The improved processing substantially linear polymers of the presentinvention produced via the procedure described earlier, as well as twocomparative resins are fabricated on an Egan blown film line using thefollowing fabrication conditions:

2 inch extruder

3 inch die

30 mil die gap

25 RPM extruder speed

460° F. melt temperature

1 mil gauge

2.7:1 Blow up ratio (12.5 inches layflat)

12.5 inches frost line height

The melt temperature is kept constant by changing the extrudertemperature profile. Frost line height is maintained at 12.5 inches byadjusting the air flow. The extruder output rate, back pressure andpower consumption in amps are monitored throughout the experiment. Thepolymers of the present invention and the Comparative polymers are allethylene/1-octene copolymers. Table VI summarizes physical properties ofthe two polymers of the invention and for the two comparative polymers:

TABLE VI Comparative Comparative Property Example 10 example 11 Example12 example 13 I₂ 1 1 1 0.8 (g/10 minutes) Density 0.92 0.92 0.902 0.905(g/cc) I₁₀/I₂ 9.45 ˜8 7.61 8.7 M_(w)/M_(n) 2 ˜5 2 ˜5

Tables VII and VIII summarize the film properties measured for blownfilm made from two of these four polymers:

TABLE VII Blown film properties Comparative Example 10 example 11Property MD CD MD CD Tensile yield 1391 1340 1509 1593 (psi) Tensilebreak 7194 5861 6698 6854 (psi) elongation (percent) 650 668 631 723Young's Modulus (psi) 18990 19997 23086 23524 PPT* Tear 5.9 6.8 6.4 6.5(gm) *Puncture Propagation Tear

TABLE VIII Comparative Property Example 10 example 11 Dart A (gm) 472454 Puncture 235 275 (grams) clarity 71 68 (percent) Haze 3.1 6.4 20°gloss 114 81 Block 148 134 (grams)

During the blown film fabrication, it is noticed that at the same screwspeed (25 rpm) and at the same temperature profile, the extruder backpressure is about 3500 psi at abort 58 amps power consumption forcomparative example 11 and about 2550 psi at about 48 amps powerconsumption for example 10, thus showing the novel polymer of example 10to have improved processability over that of a conventionalheterogeneous Ziegler polymerized polymer. The throughput is also higherfor Example 10 than for comparative example 11 at the same screw speed.Thus, example 10 has higher pumping efficiency than comparative example11 (i.e., more polymer goes through per turn of the screw).

As FIG. 5 shows, the heat seal properties of polymers of the presentinvention are improved, as evidenced by lower heat seal initiationtemperatures and higher heat seal strengths at a given temperature, ascompared with conventional heterogeneous polymers at about the same meltindex and density.

What is claimed is:
 1. A continuous process of preparing a polymerhaving a melt flow ratio, I₁₀/I₂, ≧5.63 and a molecular weightdistribution, M_(w)/M_(n), defined by the equation: M _(w) /M _(n)≦(I ₁₀/I ₂)−4.63, said process comprising continuously contacting one or moreC₂-C₂₀ olefins with a catalyst composition under continuouspolymerization conditions, wherein said catalyst composition is madefrom components comprising: (a) a metal coordination complexcorresponding to the formula:

wherein R′ each occurrence is independently selected from the groupconsisting of hydrogen, alkyl, aryl, silyl, germyl, cyano, halo andcombinations thereof having up to 20 non-hydrogen atoms; X eachoccurrence independently is selected from the group consisting ofhydride, halo, alkyl, aryl, silyl, germyl, aryloxy, alkoxy, amide,siloxy, neutral Lewis base ligands and combinations thereof having up to20 non-hydrogen atoms; Y is —O—, —S—, NR*—, —PR*—, or a neutral twoelectron donor ligand selected from the group consisting of OR*, SR*,NR*₂, and PR*₂; M is a metal of group 3-10, or the Lanthanide series ofthe Periodic Table of the Elements; and Z is SiR*₂, CR*₂, SiR*₂SiR*₂,CR*₂CR*₂, CR*═CR*, CR*₂SiR*₂, GeR*₂, BR*, BR*₂; wherein: R* eachoccurrence is independently selected from the group consisting ofhydrogen, alkyl, aryl, silyl, halogenated aryl, halogenated alkyl groupshaving up to 20 non-hydrogen atoms, and mixtures thereof, or two or moreR* groups from Y, Z, or both Y and Z form a fused ring system; and n is1 or 2, and (b) an activating cocatalyst.